I think if it was one last time I'd probably aim for a big one - substance; probably LSD - dose; high - setting; a laid back small to medium sized festival - goals - just to see
Mine would be quite like ones I read above:
400 mg synthetic mescaline, after the initial peak a decent bit of liquid acid,
maybe a little racemic K (i don't always prefer the R-ket I usually have) and nitrous on
hand and nearing the end some 2/3 MDMA 1/3 MDA.